Device for switching over the current feeding at least two electric discharge tubes containing an ionizable atmosphere



Oct. 31, 1967 E. GOMONET 3 350,601 DEVICE FOR SWITCHING OVER TH ECURRENT FEEDING AT LEAST TWO ELECTRIC DISCHARGE TUBES CONTAINING ANIONIZABLE ATMOSPHERE 7 Filed Jan. 18, 1965 2 Sheets-Sheet 1 Oct. 31,1967 E. GOMONI ET I 3,350,601 DEVICE FOR SWITCHING OVER THE CURRENTFEEDING AT LEAST I TWO ELECTRIC DISCHARGE TUBES CONTAINING AN IONIZABLEATMOSPHERE Filed Jan. 18, 1965 2 Sheets-Sheet 2 Fig. 5

United States Patent 3,350,601 DEVICE FOR SWITCHING OVER THE CURRENTFEEDING AT LEAST TWO ELECTRIC DIS- CHARGE TUBES CONTAINING AN IONIZABLEATMOSPHERE Edouard Goinonet, Paris, France,

Claude Paz et Visseaux Filed Jan. 18, 1965, Ser. No. 426,098 Claimspriority, application France, Jan. 30, 1964, 962,049, Patent 1,395,63915 Claims. (Cl. 315-90) The present invention has for its object anarrangement for switching over the current feeding at least two electricdischarge tubes containing an ionizable atmosphere, the switching beingperformed on one or several secondary coils of the transformer ortransformers feeding said tubes, in which arrangement the switch, beforeit disconnects the operative discharge tube from the correspondingsecondary coil, ensures the connection of another tube with thesecondary coil which is to feed it.

One or more of said discharge tubes may be replaced by a group of atleast two such tubes serially connected.

The shifting appearance of luminous ornamental displays and signs isgenerally controlled by connecting and disconnecting in accordance witha predetermined rhythm the primary coil of the transformers of which thesecondary coils feed the discharge tubes forming the sources of lightfor ornamental display or signboard purposes.

In order to reduce the number of transformers, it has already beenproposed to connect sequentially several discharge tubes or groups ofdischarge tubes connected in series with a same secondary coil throughthe agency of a switch. By reason of the high open circuit voltage ofthe transformers feeding the tubes and of the important energy which maybe stored in said transformers at the moment of the breaking of thecircuit, each time the switch is operated, an arcing generally appearsin the switch. Such an arcing is prevented when the feeding of one tubeis switched off only after the feeding of the next tube is provided.However, the arcing reappears as soon as a tube or group of seriallyconnected tubes cannot be ignited, for instance when a connection is cutoff or a tube is out of use. In such a case, as a matter of fact, theenergy stored in the secondary coil of the transformer when it feeds agroup of tubes in an operative condition, can no longer be dissipated inthe next group of tubes since the latter cannot be ignited. Said energyis transformed into an intense sparking in the high voltage switch therepetition of the sparks finally damaging said switch.

According to the invention, said drawback is cured by providing anauxiliary electric discharge tube containing an ionizable atmosphere,said tube connecting together those switch contact-pieces through whichthe latter is connected respectively with the different discharge tubesor groups of discharge tubes.

The accompanying drawings illustrate by way of example anddiagrammatically various embodiments of the invention.

In said drawings:

FIGS. 1, 2 and 3 are diagrams of an embodiment showing three switchingstages,

FIG. 4 is a'diagram for the successive energizing of four groups oftubes,

FIG. 5 is a diagram incorporating a transformer provided with twosecondary coils,

FIGS. 6 and 7 illustrate modifications in the connections provided forthe auxiliary tube,

FIG. 8 is a diagram of a circuit which allows obtaining manifoldluminous effects.

In the circuit illustrated in FIGS. 1, 2 and 3, a transformer 2 showinghigh magnetic leaks includes a primary coil 4 fed by a source ofalternating current 6, and a secassignor to 2 ondary coil 8. Two groupsofdischarge tubes 10, 12, 14 and 16, 18, 20 are connected in parallelwith the secondary coil 8 through the agency of a high voltage switchdesignated by the general reference number 22. Said tubes areconstituted for instance by fluorescent lamps or neon tubes.

The switch 22 includes a central contact-piece 24 connected with thesecondary coil 8 and controlled for instance by a cam driven by a smallmotor and speed reducer group (not shown) said central contact-piece 24being associated with two lateral contact-pieces 26, 28 connectedrespectively with the tube 10 and with the tube 16 and urged against aninsulating stop 34 by corresponding springs 30 and 32.

The central contact-piece 24 plays the part of the movable contact-pieceof a conventional switch while the lateral contact-pieces 26, 28 playthe part of stationary contact-pieces. Said contact-pieces will bedesignated hereinafter respectively as the movable contact-piece and thestationary contact-pieces.

In the switch position illustrated in FIG. 1, the movable contact-piece24 engages the stationary contact-piece 26 and ensures the feeding ofthe tubes 10, 12 and 14 while no current can pass through the group oftubes 16, 18, 20, since the stationary contact-piece 28 correspondingthereto is prevented by the stop 34 from engaging the contactpieces 24and 26.

In the switch position illustrated in FIG. 2, the movable contact-piece24 engages both stationary contact-pieces 26 and 28 simultaneously. Thestop 34 may or may not engage the stationary contact-pieces during saidswitch position. For the very short time, during which the two groups oftubes are connected in parallel, the current passes through both groups,however with a very unequal distribution even if the electriccharacteristic features of the two groups are very similar. No sparkingis produced since no circuit is broken.

When the next switch position illustrated in FIG. 3 is reached, thecontact-piece 24 has moved off the contactpiece 26 while remaining incontact with the contact-piece 28. The sparking in the switch iseliminated or minimized since the energy stored in the transformer mayreadily flow through the tubes 16, 18 and 20.

This being done, and the switch 22 being thereafter set in succession inthe positions illustrated in FIGS. 2 and 1, there is obtainedsimultaneously the extinction of the group 16, 18, 20 andstraightforward starting of the group 10, 12, 14 without any sparking orwith a very re duced sparking.

In order to break a contact in the switch with a minimum sparking, it isan advantage to produce an ionization in the tubes fed by thecontact-piece which has just been closed. To this end, it is necessaryfor the tubes to have been subjected at least to one peak voltage duringthe period for which the two stationary contact-pieces aresimultaneously closed, whatever may be the location of the moment atwhich the contact closes with reference to the voltage phase. Thisresult is obtained by keeping simultaneously the two contact-pieces intheir closed condition during at least one half period for example atleast one hundredth of a second in the case of 50 cycle current. On theother hand, it is preferable for said duration of connection in parallelof the two groups of tubes, to be hardly perceptible for observers andtherefore, it is of interest to make it at least less than one twentiethof a second.

In order to prevent any damage to the switch 22 when a series of tubescannot be ignited, an auxiliary tube 112 is connected across thecontact-pieces 26 and 28 of the switch.

The auxiliary tube is constituted for instance by a comparatively shortdischarge tube with cold electrodes, con- I group of tubes taining amass of a rare gas under a pressure of a few tens centimeters ofmercury.

Assuming first that the electric system is in a proper operativecondition, operation of the switching device is as follows, startingfrom the position illustrated in FIG. 3.

At the start, the tubes 16-, 18 and 20 are fed and the differencebetween the characteristic electric feature of the groups 16, 18, 20 onthe one hand and 10, 12, 14, 112 on the other hand, is such that thecurrent in the tubes of the latter group is negligible. The operation ofthe switch 22 first short-circuits the tube 112 and sets in parallel thegroups 16, 18, 20 and 10, 12, 14 after which the tubes 10, 12 and 14remain directly connected across the terminals of the transformer whilethe tube 112 is inserted in series with the tubes 16, 18, 20 so that thecurrent in the latter is negligible, while practically all of thecurrent passes through the tubes 10, 12 and 14. If, on the contrary, oneof the tubes, 10, 12 and 14 is no longer capable of operating, thesecond stage in the operation of the switch 22 would insert the tube 112in series with tubes 16, 18, 20 and the energy stored in the transformerwould be spent in said tubes instead of producing destructive sparks inthe switch 22.

In the case where it is desired to feed in succession a number n ofgroups of tubes inserted in series, It being an integer above 2, it ispossible to design a switch similar to the switch 22, but provided inthis case with n outputs. Said switch should operate in a sequence suchthat one is disconnected only after the switch has provided for theconnection of the group which is to be ignited immediately afterwardsand the case is obviously the same when one or more groups include onlyone tube each. It is also possible to use, as illustrated in FIG. 4, asimpler high voltage switch similar to the switch 22..

FIG. 4.illustrates an embodiment adapted to energize in succession fourgroups of tubes, 36+38+40,

48+50+52, 54-1-56-1-58. The two first groups are designated by thegeneral reference 60 and the two last groups by the general reference62.

For each system of two groups, circuit breakers 68, 70, 72 and 74control the connection of the groups forming the corresponding system.These circuit-breakers are actuated only during the lapse of time duringwhich the switch 22 does not allow any current to pass through thesystem of groups of tubes considered. In FIG. 4, the switch 22, whichhas just been brought from the position for which it allows current topass through the group 54, 56, 58 of the system 62 has been brought intothe position for which it causes current to pass through the group 36,38, 40 of the system 60. It is then possible to close the circuitbreaker 72 and to open the circuit breaker 74 so that at the next returnof the switch 22. towards the system 62, the group 48, 50, 52 isignited. When the switch 22 is in the position energizing the system 62,it is possible to operate the circuit-breakers 68 and 70.

The movement of said circuit-breakers is automatic and is controlled bythe same motor as the reversal of the switch 22 so that the operation ofsaid contact-breakers is always performed reliably during a phase forwhich the corresponding circuits are at zero current.

An auxiliary tube 112, playing the same part as in the circuitillustrated in FIGS. 1, 2 and 3, is connected across the system 60 and62.

It is also possible to use an auxiliary tube when several secondarycoils feed the discharge tubes.

FIG. illustrates a circuit of such a type comprising a transformershowing high magnetic leaks and including a primary coil 80 and twosecondary coils 82 and 84, which latter feed respectively thecorresponding groups of tubes 86, 88, 90 and 126, 12.8, 130. The highvoltage switch is constituted in the present case by a rocking mercuryswitch 106 carrying an amount of mercury sufiicient for shortcircuitingthe extreme contact-piece 108, 110 when the switch is in itsintermediate position.

The point common to the secondary coils 82 and 84 is grounded and anauxiliary tube 112 is connected across the terminals 108, 110 of theswitch. The secondary coil 84 is coupled with the primary coil to thesame extent as the secondary coil 82.

If, starting from the position illustrated in FIG. 5, the switch rockstowards the right and assuming the group 86, 88 and 90 is defective andcannot be ignited, the circuit is closed as follows, starting from thepoint common of the secondary coils:

Line 132, mass of mercury between the cooperating contact-pieces 124 and110, lines 122 and 120, tube 112, line 118 and 116, the tubes 130, 128,126 which were ignited during the preceding stage, secondary coil 84.

In order that the switch 106 may operate properly, the magnetic couplingbetween the secondaries 82 and 84 should be sufficiently close.Experience has shown that it is necessary to satisfy the relationship:

E2 075 E1 where E and E are the no-load voltages of one of the twosecondary coils and of the other respectively, while E and E are thevoltages obtained, when said one secondary coil feeds, after ignition,the corresponding tube or tubes, for said one and said other secondarycoil respectively.

The safety obtained through the agency of the auxiliary tube 112 may beincreased. For instance, it is possible to connect a similar tube inshunt across said tube; when one of the two auxiliary tubes becomesdamaged or has been damaged by some accident, the other tube remains toplay the part of the first tube. It is also possible to control, throughthe agency of the current passing in the auxiliary tube in the case of amishap, a relay which switches off the current feeding the transformeror transformers.

FIGS. 6 and 7 illustrate, by way of example, two circuit sections forwhich both such supplementary safety means are used simultaneously. Inboth cases, the auxiliary supplementary tube is designated by thereference number 136 and the sensitive member controlling the relayacting as a circuit disconnect, such for example as a Winding or abimetallic strip, is illustrated merely by a block 138. The portion ofthe circuit illustrated is substituted for the one which on FIGS. 1 to 5includes the switch 22 or 106, the tube 112 and their connecting wires.

In the circuit section illustrated in FIG. 6, the tube 136 is connecteddirectly shuntwise across the tube 112', the sensitive member 138 isconnected in series with both tubes and the system including the tubes112 and 136 and the sensitive member 138 is connected shuntwise acrossthe extreme contact-pieces 108 and 110 of the switch 106 under load. Thesensitive member 138 functions in the event of damage to the tube 112 orthe tube 136.

In the circuit section illustrated in FIG. 7, the tubes 112 and 136 havestarting voltages of different values. The sensitive member 138 isconnected in series with the tube of which the starting voltage is thehigher, say the tube 136. The other tube 112 is connected in shunt withthe system including the tube 136 and the sensitive member 138. In caseof a mishap, the auxiliary tube 112 is that which is normally ignitedand it feeds current towards the luminous tubes which can start. If nowsaid tube 112 cannot be ignited or is ignited only with difficulty, theauxiliary tube 136 is ignited and current passes then through thesensitive member 138 which switches off the feeding of energy into thetransformer.

The possible embodiments of the invention may be used to produce asuccession of illuminations based upon those disclosed above. It ispossible to resort to a number of high voltage switches operating in themanner described with reference to FIGS. 1, 2 and 3 for instance. Thecircuit illustrated in FIG. 8 includes four high voltage switches 140,142, 144, 146 illustrated in a highly diagrammatic manner and actuatedperiodically by a motor and speed reducer group in accordance with apredetermined programme. It is thus possible to obtain a number ofvaried combinations during a cycle.

For each switch, the contact-pieces connected with different dischargetubes are interconnected by an auxiliary discharge tube. For sake ofsimplification of FIGURE 8, only the auxiliary tube 112 is illustrated,which tube interconnects the contact-pieces of the switch 146, saidcontact-pieces being connected respectively with the tubes 148 and 150.

The circuits illustrated may be modified without departing from thepresent invention. For instance, the switch 22 or 106 under load may bebipolar, for instance in the case of displays operating in the open, indamp countries. The positions of the two elementary switches for whichtwo groups of tubes are connected simultaneously, are transientlycoextant.

What I claim is:

1. An arrangement for switching from one circuit to another of a pair ofcircuits, each circuit containing at least one main discharge tubehaving an ionizable atmosphere, comprising an auxiliary tube having apair of electrodes in an ionizable atmosphere, said auxiliary tube beingconnected in series with the main tubes, and switch means having a pairof terminals, one terminal being connected to one of said electrodes,respectively, said switch means selectively connecting one of said pairof circuits to said source of energy.

2. An arrangement as defined in claim 1 further including means formomentarily simultaneously connecting both said circuits to said source.

3. An arrangement as defined in claim 1 further including means forsimultaneously connecting both said circuits to said source for a periodthat is at least of a second.

4. An arrangement as defined in claim 1 further including means forsimultaneously connecting both said circuits to said source for a periodequal to at least onehalf the period of the frequency of the source.

5. An arrangement as defined in claim 1 further including means forsimultaneously connecting both said circuits to said source for aninterval of time between a half period of the feed voltage and of asecond.

6. A switching arrangement as defined in claim 1 further including asecond auxiliary tube in shunt with the first mentioned auxiliary tube.

7. A switching arrangement as defined in claim 6 further including arelay in series with at least one of said auxiliary tubes and meansconnecting said relay to the primary winding of the transformer fordisconnecting the primary winding from an energy source when the currentthrough the relay increases by a predetermined amount.

8. A switching arrangement as defined in claim 6 further including arelay in series with both auxiliary tubes and means operative by saidrelay for disconnecting the primary winding of the transformer from anenergy a source of energy source when the current through the relayincreases by a predetermined amount.

9. A switching arrangement as defined in claim 6 wherein one of saidauxiliary tubes has a higher starting voltage than the other, a relay inseries with said tube of higher starting voltage and means operative bysaid relay for disconnecting the primary winding of the transformer froman energy source when the current through the relay increases by apredetermined amount.

10. An arrangement for switching the secondary winding of a transformerfrom one circuit to another of a pair of circuits, each circuitcontaining a plurality of discharge tubes in series and each tube havingan ionizable atmosphere comprising means connecting one end of each ofsaid circuits to one end of the secondary winding, an auxiliary tubehaving an ionizable atmosphere, and switch means for selectivelyconnecting said auxiliary tube in series with one of said pair ofcircuits and the other end of the secondary winding and for connectingthe other of said pair of circuits directly to said other end of thesecondary winding.

11. An arrangement for switching the secondary winding of a transformerfrom one circuit to another of a pair of circuits, each circuitcomprising parallel branches havplurality of discharge tubes enclosingan ionizable in series in each branch, comprising a circuit forconnecting the branches to one end of the secondary winding, anauxiliary discharge tube having an ionizable atmosphere, and switchmeans for selectively connecting said auxiliary tube in series with oneof said pair of circuits and the other end of the secondary winding andfor connecting the other of said pair of circuits directly to said otherend of the secondary winding.

12. An arrangement as defined in claim 11 further including a secondauxiliary tube in shunt relation with the first mentioned auxiliarytube.

13. An arrangement as defined in claim 11 further including means forselectively operating the circuit breakers in the branches of one of thecircuits when the current flowing therein is zero.

14. A switching arrangement for a pair of circuits each containing atleast one discharge tube having an ionizable atmosphere and eachconnected in series with one secondary winding of a transformer having apair of secsald auxiliary tube being connected in series with both saidcircuits, and switching means for momentarily selectively connectingsaid auxiliary tube in series with one of said circuits with respect toa reference point exclusive to the other circuit.

15. A switching arrangement as defined in claim 14 further including asecond auxiliary tube in shunt with the first mentioned auxiliary tube.

N 0 references cited.

JOHN W. HUCKERT, Primary Examiner. R. F. POLISSACK, Assistant Examiner.

1. AN ARRANGEMENT FOR SWITCHING A SOURCE OF ENERGY FROM ONE CIRCUIT TOANOTHER OF A PAIR OF CURCUITS, EACH CIRCUIT CONTAINING AT LEAST ONE MAINDISCHARGE TUBE HAVING AN IONIZABLE ATMOSPHERE, COMPRISING AN AUXILIARYTUBE HAVING A PAIR OF ELECTRODES IN AN IONIZABLE ATMOSPHERE, SAIDAUXILIARY TUBE BEING CONNECTED INSERIES WITH THE MAIN TUBES, AND SWITCHMEANS HAVING A PAIR OF TERMINALS, ONE TERMINAL BEING CONNECTED TO ONE OFSAID ELECTRODES, RESPECTIVELY, SAID SWITCH MEANS SELECTIVELY CONNECTINGONE OF SAID PAIR OF CIRCUITS TO SAID SOURCE OF ENERGY.